In conventional fuel delivery systems for internal combustion engines, a constant-delivery fuel pump supplies fuel under pressure from a tank to a fuel rail positioned on the engine. A plurality of fuel injectors are mounted between the fuel rail and the engine intake manifold, with the injector nozzles being positioned adjacent to the fuel/air intake ports of the individual engine cylinders. The fuel injectors are individually electromagnetically actuated by an engine control unit as a function of operating conditions and parameters at the engine.
A major cost associated with fuel delivery systems of the described character lies in the individual fuel injectors, and in the complexity of electrical conductors that connect the fuel injectors to the engine's electronic control unit. In addition, the fuel injectors are subject to wear, and may eventually feed differing quantities of fuel to the cylinders even when actuated for nominally identical time durations, thus resulting in less than optimum engine operation. Furthermore, conventional fuel injectors present additional difficulties when employed in conjunction with so-called alternative fuels. Fuels of this character have lower lubricity than conventional gasoline fuels, increasing wear at the individual injectors. The injector wear parts may be constructed of stainless steel to reduce wear, but this greatly increases cost. Moreover, because of lower energy content of alcohol-based alternative fuels, for example, the injectors must have a larger fuel opening and/or remain open longer than would otherwise be desirable in operation with gasoline. Thus, conventional fuel injectors are not well suited for use in association with engines intended for operation with alternative fuels having differing potential energy contents.
U.S. Pat. No. 3,664,318 to Giuffra discloses a fuel injection system not requiring conventional fuel injectors. The system includes a distributor housing fixed in a housing above a distribution cavity. A shaft is rotatably mounted in the housing and passes through the distribution cavity and the distributor housing. The distributor housing defines an aperture for each cylinder of an engine, and each aperture connects the distribution cavity with a fuel outlet of the housing. A flat, plate-like distributor rotor is secured to the shaft within the distribution cavity, blocking the apertures of the distributor housing. During operation, the distribution cavity is filled with fuel and the shaft and the distributor rotor are rotated. The distributor rotor defines a rotor aperture that sequentially aligns with each of the apertures in the distributor housing as the rotor rotates, so that fuel can pass to the fuel outlets and to fuel injectors in the engine cylinders.
One drawback of the Giuffra system is that the distributor cavity must be filled with fuel during operation before the fuel is distributed to the fuel outlets. Filling the distributor cavity, however, requires a complex fuel pumping means which adds many parts and increases the complexity of the distributor. What is desired, therefore, is a distributor that distributes fuel directly to fuel outlets without requiring that the distributor cavity be filled with fuel.